3" vs 2 3/4" Exhausts

[wsp Member Find all posts View Profile Close wsp]

I have my one booked in for a 3 inch Taipan XP and a chip tune on the 23rd of this month. They do a before and after dino run so will be interesting to see the difference.

[ToeEdge Junior Member Find all posts View Profile Close ToeEdge]

Long term report on my 3" Genie system.
Generally, I've noticed no improvement in fuel economy.
On performance gains - When I accelerate hard, I lose all my boost between gear changes, particularly between 3rd and 4th. I assume due to lack of back-pressure. General sedate driving is good.
I'm also currently in discussion with them trying to rectify an issue with the pipe hitting the suspension control arm over the diff and also vibrating on the rear fuel tank guard. They've said they'll be shipping me a new rear section... but I'm yet to see it. If I were buying one now, I'd go for 2 3/4".

[shodown Senior Member Find all posts View Profile Close shodown]

Long term report on my 3" Genie system.
Generally, I've noticed no improvement in fuel economy.
On performance gains - When I accelerate hard, I lose all my boost between gear changes, particularly between 3rd and 4th. I assume due to lack of back-pressure. General sedate driving is good.
I'm also currently in discussion with them trying to rectify an issue with the pipe hitting the suspension control arm over the diff and also vibrating on the rear fuel tank guard. They've said they'll be shipping me a new rear section... but I'm yet to see it. If I were buying one now, I'd go for 2 3/4".

Hey Mate - I had an issue with my 2.75" hitting a bolt thread from an exhaust hanger under certain RPM. Robsons in Perth had to remove back section, cut off the excess thread and re-install.

Beaudesert did not include any instructions / warning of it, but I thought they should have picked it up on test drive.....

[ScoticusMaximus Member Find all posts View Profile Close ScoticusMaximus]

All,
Thought i would give a quick update; its about a year now since i picked up my 2.75" outlaw system from Right Price at slacks creek (Replaced a 3" sterling system). Since installing it i have done cape york last year and the victorian high country earlier this year (also doing central Aus and Simpson in August). Could not be happier with the result of the change, and the exhaust still looks great too (Ceramic dump pipe is pretty). I highly recommend the 2.75 instead of the 3, much better low down grunt and torque through the rev range, glad i changed it out.
Cheers,
Scott.

[Vaelen Junior Member Find all posts View Profile Close Vaelen]

Back in the 90s I used to race a petrol turbo escort (when I lived in the UK) and the general consensus was with a turbo no back pressure is required (different for NA vehicles) so a short fat exhaust to let as much gas out as quickly as possible was the best way to go.... maybe the last 20 years things have changed, or maybe diesels are different... but in my experience bigger is better for performance.

In general, this is still very much the case. NA vehicles have to have back pressure to assist with port closure. FI (forced induction) vehicles don't have that issue, however, the thickness of the exhaust can affect performance based on turbo size and response.
For a Turbonetics T72 (also known as "the mother in law"), you can have whatever exhaust you want - including no exhaust - as it requires a massive amount of airflow. Whereas a T4 is small and compact and will spool up pretty quick, but it requires a more linear flow and therefore would be better suited to a smaller pipe. Also remember that petrol cars rev higher and as such can have completely different setups to a diesel.

For a standard D4d motor, I'd go 2.75", maybe even 2.5"

[Palmer Advanced Member Find all posts View Profile Close Palmer]

All,
Thought i would give a quick update; its about a year now since i picked up my 2.75" outlaw system from Right Price at slacks creek (Replaced a 3" sterling system). Since installing it i have done cape york last year and the victorian high country earlier this year (also doing central Aus and Simpson in August). Could not be happier with the result of the change, and the exhaust still looks great too (Ceramic dump pipe is pretty). I highly recommend the 2.75 instead of the 3, much better low down grunt and torque through the rev range, glad i changed it out.
Cheers,
Scott.

G'day Scott, is your rig 1kz or 1kd ?

Cheers

[Palmer Advanced Member Find all posts View Profile Close Palmer]

Just re-read whole thing and saw you are running 1kz.

I'm looking at upgrading my 1kd at some stage, so will chase and up which way to go for that.

[crowey Member Find all posts View Profile Close crowey]

Sorry to dig up an old thread but i have a dilemma!

Ive spoken with 2 different exhaust companies here in Adelaide regarding the fitment of dump pipe and new section back to the first flange (just behind the cross member) and removing the small hotdog thing also.

One said to do 2.5" dump and 2.5" pipe back to the flange and the other said 3' dump and pipe.

04 1kz with DP chip set on 6 with boost set on 14psi

i don't want to do a full system, just the dump and may as well go that little bit further to the flange.

thoughts?

[REN470 Member Find all posts View Profile Close REN470]

In my opinion 3 " is too big for a full system and prone to droning but as your only doing the front section who knows? I've seen quite a few dyno results from exhaust companies both diesel and petrol and IMO the result isn't worth the cost

[t303 Senior Member Find all posts View Profile Close t303]

Recent threads that have relevant info:
http://www.pradopoint.com/showthread...-have-a-DPChip
http://www.pradopoint.com/showthread...amp-VIDEO-UP**

cheers
Steve

[clarkie383 Member Find all posts View Profile Close clarkie383]

I ran a full 3" exhaust from Scotts Rods and no drone at all.
Muffler was about 1/3 the size of original and was a bit worried.

We since used one of theirs on a cruiser with the same joy.

[mikenzaa Junior Member Find all posts View Profile Close mikenzaa]

i just put on a redback extream duty for my 1kz. Came with a large muffler and muffler delete pipe. going by my redarc gauge my egts are down by 80 degrees so im sitting on 300 degrees normal driving. Highway driving im sitting on 350 degrees and witha heav foot 400+ degrees. Its a straight 3" system.